Allow setting config drive option when launching instance

This patch adds a "Configuration Drive" checkbox to the Advanced tab
of the Launch Instance workflow, if the config drive extension is
supported. This allows setting the config drive option when launching
an instance.

Change-Id: Ib4e4e18251f4f024a61dabb646cda79a7c88582d
Closes-Bug: #1366842
Merge "Allow setting config drive option when launching instance"